macos - `git difftool -d` get 'file does not exist' error on mac

Question

I am trying to use command git difftool -d for a folder diff.

The command get diff list successfully (show in FileMerge.app). But when I try to open each diff file. I get file does not exist error.

Output log:

$ git difftool -d 
merge tool candidates: opendiff kdiff3 tkdiff xxdiff meld kompare gvimdiff diffuse ecmerge p4merge araxis bc3 codecompare emerge vimdiff

Image:

I am using git version 1.8.1.1 on mac OS X 10.9. Thanks.